The present invention relates to vehicles with lean control systems. In particular, the present invention relates to a vehicle with a hydraulically-actuated primary and auxiliary lean control system coupled to a vehicle leaning suspension system for enhancing vehicle stability.
In a two-wheeled motorcycle moving at a speed within the range of approximately 0-15 mph, a combination of “in-phase” steering and lean angle control is used to achieve directional control of the motorcycle. As the vehicle speed increases, it is increasingly necessary to use “counter” or “out-of-phase” steering in conjunction with lean angle control to achieve directional control.
In a steady-state turn at speeds greater than approximately 15 mph, the net moment at the motorcycle center of gravity (CG) and the handlebar moment applied by the operator are both zero. In this case, the lean angle is such that the moment due to gravity and the moment due to lateral acceleration of the motorcycle are equal and opposite. An example of this is that, for a lateral acceleration on 1 G, a lean angle of approximately 45° is required for equilibrium in a steady state turn.
Above speeds greater than approximately 15 mph, the operator is able to apply an “out-of-phase” moment to the handlebar which, through wheel gyro effect, will result in moment about the motorcycle CG resulting in a corresponding rate of change of the lean angle. The resulting change in lean angle (or camber) causes the motorcycle to turn, thereby increasing lateral acceleration. By adjusting the handlebar moment, the operator is able to increase the rate of change of the lean angle, decrease the rate of change of the lean angle, or hold a steady-state condition with constant turn radius.
A three-wheeled motorcycle, or “trike”, will be kinematically unable to achieve the lean angles possible with the two-wheeled motorcycle. For this reason, a different direction control strategy is required to facilitate vehicle stability during turns.